2.26.126: debugging ecl, upgrade, etc.

Don't key upgrade attempt on source-registry, since things can also change
in the central-registry, etc.
Also rename required-files to direct-dependency-files
Improve the new convenience function pattern to work with operation initargs.
Implement getcwd on all platforms.
Actually catch sb-grovel messages.

Tests: make u l=ecl instead of make test-upgrade lisp=ecl
Tests: put the setup around the script, not inside;
Tests: start using globals, much easier for debugging